A semiconductor device (SiC device) using a silicon carbide crystal has such characteristics as high withstanding pressure and high temperature operation, in comparison with the conventional semiconductor device (Si device) using a silicon crystal. The SiC device shows such an excellent performance based on basic characteristics of an SiC crystal. Carbon atoms are contained in the SiC crystal, whereby the distance between the atoms is reduced to realize the stronger coupling, thereby increasing the size of a band gap of a semiconductor twice or more. As a result, the withstanding pressure is increased to not less than twice electric field, and the semiconductor characteristics are maintained until reaching a high temperature.
Although the SiC crystal has an extremely excellent basic characteristics, the crystal growth is very difficult, and crystal defect is easily caused. Therefore, there is a problem that the hole diameter of the substrate (wafer) is hard to be increased. At present, an Si substrate (Si wafer) with a hole diameter of 5 to 8 inches is mostly used, while a very expensive 4H—SiC substrate (SiC wafer) with a hole diameter of 2 to 3 inches is mostly used. For this reason, in carrying out development of the semiconductor device, in many cases, the 4H—SiC substrate is cut into small chips to carry out trial manufacture, and thus, it is very difficult to obtain basic data for mass production.
When the development of the mass production techniques in the SiC device is carried out, it is very effective to use a device group used in the manufacturing of the Si device. In addition, know-how in mass production techniques used for the manufacturing of the Si device can be effectively utilized. Currently, the SiC device can be miniaturized to about 0.5 μm in the latest technology, and therefore, the microfabriaction can be applied to the SiC device using an existing Si device manufacturing device.
However, as above mentioned, in the SiC crystal, only a substrate with a hole diameter of up to about 3 inches can be produced. Therefore, it is difficult to use an existing Si device manufacturing device. In order to use the Si device manufacturing device, Japanese Patent Application Laid-Open (JP-A) No. 11-87200 proposes that, in an existing manufacture line for the Si device, a semiconductor substrate with an SiC substrate with a small hole diameter laminated to an Si substrate is processed in a similar manner to the Si substrate with a larger hole diameter.
However, the method described in JP-A-11-87200 has a problem that, since the SiC substrate and the Si substrate are directly applied with each other by an SDB (silicon direct bonding) method, the alignment between the SiC substrate and the Si substrate, or the alignment among plural SiC substrates is difficult.
The SiC substrate and the Si substrate have a cutout called an orientation flat in accordance with the in-plane crystal orientation. The substrates having the same size can be processed while the position and the crystal orientation are aligned using the orientation flat. However, in the SiC substrate and the Si substrate having different sizes from each other, it is difficult to align the position and the crystal orientation. If the position and the crystal orientation of the SiC substrate are not fixed, it is difficult to process in an existing device manufacturing device.